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IC! 8855
Bureau of Mines Information Circular/1981
Uranium Mine Ventilation Costs
By Robert C. Bates
UNITED STATES DEPARTMENT OF THE INTERIOR
Information Circular 8855
Vl
Uranium Mine Ventilation Costs
By Robert C. Bates
UNITED STATES DEPARTMENT OF THE INTERIOR
James G. Watt, Secretary
BUREAU OF MINES
Robert C. Horton, Director
«&
&
4^ ^*
As the Nation's principal conservation agency, the Department of the Interior
has responsibility for most of our nationally owned public lands and natural
resources. This includes fostering the wisest use of our land and water re-
sources, protecting our fish and wildlife, preserving the environmental and
cultural values of our national parks and historical places, and providing for
the enjoyment of life through outdoor recreation. The Department assesses
our energy and mineral resources and works to assure that their development is
in the best interests of all our people. The Department also has a major re-
sponsibility for American Indian reservation communities and for people who
live in Island Territories under U.S. administration.
This publication has been cataloged as follows:
Bates, Robert C
Uranium mine ventilation costs.
(Information circular ; 8855)
Bibliography: p. 18.
Supt. of Docs, no.: I 28.27:8855.
1. Uranium mines and mining— Safety measures. 2. Mine ventila*
tion— Costs. I. Title. II. Series: Information circular (United States.
Bureau of Mines) ; 8855.
TN295.U4 622s [338.2'3]
81-607862 AACR2
For sale by the Superintendent of Documents, U.S. Government Printing Office
Washington, D.C. 20402
CONTENTS
Page
Abstract 1
Introduction 1
Background 2
FRC staff report 2
RMC report 4
ADL study 7
Analysis 9
Applications 12
Cost of other control measures 16
Conclusions 17
References 18
ILLUSTRATIONS
1. Cost per ton for ventilating uranium mines 10
2. Costs for ventilating uranium mines versus average annual exposure
with regression line 12
3. Projected radiation control cost for different Consumer Price
Indices and average annual exposures 14
4. Project radon-daughter control costs versus limiting miner exposure
WLM for several Consumer Price Index values 15
TABLES
1. Ventilation cost estimates, 11-mine study, 1965 3
2. Ventilation cost estimates, 3-mine study 3
3 . Modified WL-control cost for three smaller mines 5
4. Radon-daughter control costs for five large uranium mines 6
5. Costs and radiation levels for various degrees of control 8
6. Federal Radiation Council Report 8 uranium mine ventilation cost
data converted to 1967 dollars per ton 9
7. Uranium mine ventilation cost data from Spencer converted to
1967 dollars per ton 10
8. Average ventilation costs and working place radon-daughter
concentrations 11
9. Consumer Price Index (1967 = 100) 13
10. Cost per ton at CPI = 250 (1980$) for several average WLM exposures 13
11. Cost per ton at CPI = 250 for several limiting miner exposures WLM. 15
12. Cost for radon control, from Kown 16
URANIUM MINE VENTILATION COSTS
by
Robert C. Bates1
ABSTRACT
This Bureau of Mines report converts published data on the cost of venti-
lating uranium mines to a common price base and analyzes these data to deter-
mine the cost per ton of uranium ore at various levels of radiation exposure
control. There appears to be an exponential increase of cost as the radiation
level is lowered. The 1967 base costs are extrapolated to present dollars,
and some cost comparisons are given for other radiation control measures.
INTRODUCTION
Since about 1950, the Bureau of Mines has been concerned about radon-
daughter concentrations in uranium mines. For a considerable time, this
interest was primarily oriented toward control by ventilation. Ventilation is
the most common airborne-radiation control measure used in uranium mines.
However, as the mines become deeper and larger, ventilation costs increase
tremendously and all available radiation control methods must be used to help
reduce the radiation hazards.
In 1973, the Bureau began investigating other methods to control
airborne-radiation levels and reduce ventilation requirements. Laboratory,
field, and theoretical evaluations were made of sealants, bulkheading, radon
removal, overpressurization, and radon-daughter removal. Costs were deter-
mined for several control techniques. For example, the cost for removing
radon from the air was found to be prohibitive (2).2
In 1973, a Bureau study was performed of data from three reports (_1, b_>
10) to estimate the cost of mine ventilation in terms that could be related
to control measure costs. These were the only reports that had seriously
discussed the cost of ventilating uranium mines. Since then, a study of
procedures for setting standards for radon-daughters has become available (5).
It evaluated the information in the three previous reports and, among other
Supervisory mining engineer, Spokane Research Center, Bureau of Mines,
Spokane, Wash.
2Underlned numbers in parentheses refer to items in the list of references at
the end of this report.
things, developed an exponential equation for ventilation costs. The informa-
tion given in the literature is not directly applicable for cost comparisons.
Therefore, the following text describes these three studies, describes the
analysis methods, compares the results with those of Cross (5), projects the
costs for various radon-daughter exposure limits, and comments on some costs
of radon and radon-daughter control measures.
BACKGROUND
The three reports studied (1_, 6^, 10) had been sponsored by the Federal
Radiation Council. The analysis base and philosophy for each were somewhat
different, thus making direct comparisons difficult. For example, three dif-
ferent parameters were used as the exposure bases for the three reports — aver-
age working level,3 mine index, and "last man" working level. The mine
average WL might or might not be representative of the miners' exposure,
because extremely low values in haulageways or intake shafts can be averaged
with the supposedly higher ones in the stopes. A more representative value
for the person's exposure is the mine index, which uses the weighting of occu-
pancy time and the number of persons involved to calculate the average. The
third concept, the "last man" working level exposure, represents the highest
annual exposure recorded for any underground personnel. The ventilation costs
are also given in two different ways, dollars per ton of ore produced and
dollars per pound of u^Os* The information available in these reports is
described briefly in the following paragraphs.
FRC Staff Report
A Federal Council (FRC) staff report (6^) summarizes quite a bit of the
information available on the radiation problem in uranium mines. Although
various control methods were available, ventilation was the most important.
Since published information on ventilation costs was not available, the FRC
staff requested a number of uranium mining companies to carry out ventilation
cost studies. As they state (6^, p. 34), "These estimates are intended to
illustrate the general magnitude of cost in a few selected mines and are not
applicable to the industry as a whole." The studies were divided into two
groups. One covered 11 larger underground mines that accounted for more
than 20 pet of the U.S. uranium ore production, and the other group covered
3 mines that produced about 2 pet of the national total.
An exposure index was developed for the first group using time-weighted
average exposures that were weighted by the number of persons involved in each
of the worker categories. Estimates were made of the radon-daughter concen-
trations for minimal ventilation, and costs were tabulated for various levels
of radiation control. Ventilation and operating costs were projected over a
10-year period. Table 1 in their report is repeated here as table 1.
3 "Working level" (WL) means any combination of the short-lived radon daughters
in 1 liter of air that will result in the ultimate emission of 1.3 x 105
million electron volts (MeV) of alpha energy.
TABLE 1. - Ventilation cost estimates, 11-mine study, 1965 (6)
(Million dollars)
Investment
Operating cost
Total cost
Estimated mine
cost
(10-year est.)
( 10-years)
index WL
Past experience
3.9
7.9
11.8
*2
Estimated ventilation
cost without radon
2.0
2.8
4.8
210
Additional cost for
radon control from
1.9
5.1
7.0
Estimated additional
cost to reduce from
1.5
6.0
7.5
1
Total cost to control
at 1 WL — 10 years..
19.3
^Composite mine index for 1965.
2Estimate of what the average WL concentration would be with normal
ventilation practices.
The second group of three mines was considerably different from the
11 mines in geology, depth, extent of working, productive capacity, arrange-
ment of passageways, numbers of openings, and so on. The reporting of the
information was also different. Ventilation and operating costs were pro-
jected over a 6-year period instead of a 10-year period, and the working-level
values were reported as 1-year averages, rather than the mine index value used
for the 11-mine study. Table 2 of the FRC staff report (6) is given in its
entirety as table 2 in this report.
TABLE 2. - Ventilation cost estimates, 3-mine study (6)
(Thousand dollars)
Investment
cost
Oper. cost
(6-year est.)
Total cost
(6-years)
Average
concentration,
WL
Past experience:
361
321
75
120
85
50
481
406
125
1IA
ll.5
11.5
757
63
66
6
255
21
18
4
1,012
84
84
10
Estimated for case of
minimum ventilation:
25-20
135
43
178
Average WL concentrations in 1965.
2Estimate of what the average WL concentrations would be with normal
ventilation practices.
RMC Report
Spencer (10) of the Resource Management Corp. (RMC) examined a number of
items, including costs, associated with the control of radon daughters in ura-
nium mines. Although literature was collected, much of the information came
from personal discussions with knowledgeable government and industry people.
From these discussions, Spencer decided to limit their studies to the Colorado
Plateau region (Uravan mineral belt and Ambrosia Lake). Their evaluations
also led RMC to the conclusion that only two approaches, historical and mod-
eling, appeared usable for cost estimating. Historical data could provide a
relationship between cost and working levels from which they could extrapolate
to the average mine with a 0.3-WL concentration. Although this technique has
a number of inadequacies stemming from the wide range in the characteristics
of the mining operations supplying the data, it was possible for RMC to
arrive at some figures in a very short time. The modeling approach, because
of the complexity of the mining process itself, was too complex for the short
time period of the study. Therefore, data were requested and received from
eight operating mines (three small and five large) for 3 years of production,
1966, 1967, and 1968.
The three small mines had relatively small output tonnages but fairly
large underground areas. Costs included supplies, labor, power, air courses,
and capital investments. Capital and ventilation costs for drifts and raises
were amortized over a 5-year period. The capital expenditures were reportedly
amortized over a 10-year period. A summary of their data is given in table 3.
The radon-daughter concentrations are given as average working levels.
TABLE 3. - Modified WL-control cost for three smaller mines (10)
Mine and year
Ore output,
10 3 tons
Average con-
centration, WL
Cost per ton
of ore1
Modified cost
per ton of
ore2
Mine A: 3
1966
12
9.4
7.7
44.0
3.0
2.2
34.1
36.2
29.3
16.7
16.2
13.1
2.2
2.1
.7
3.1
2.1
.6
1.3
1.3
.5
1.66
1.50
.55
$0.33
1.10
.51
.47
1.38
.90
.21
.47
2.19
.26
.65
1.79
$0.28
1967
.64
1968
.57
Mine B:3
1966
.43
1967
1.08
1968
.89
Mine C : 3
1966
.20
1967
.44
1968
1.47
Average: 5
1966
.24
1967
.52
1.26
Capital expenditure written off over 10 years; some totals in RMC report (10)
appeared to be wrong, so recalculated values were used.
2Cost of air courses amortized over 5 years.
3Data are for 1st half of year.
4 1966 output of mine B was not available; assumed by extrapolation,
individual mine data averaged by tonnage ore output.
The owners of the five larger mines reported total capital assets in the
original data, but Spencer used only the incremental capital expenditures for
the period of interest. Therefore, certain capital costs did not contribute
to the 1966-68 working level reductions. However, the improvements in concen-
tration are shown as functions of new capital investments and increased oper-
ating and maintenance costs. The working level averages given in their tables
are not based on personal exposures but are simple arithmetic averages of per-
iodic readings taken by the mine operator in the occupied areas of the mine.
In one sense, since most of the underground workers are in areas of higher
radon concentration, the average exposure might be higher than the data indi-
cate. Further analysis (based on some additional information supplied by the
owners) indicated that, for the period studied, average exposures and aver-
age working levels were equal. A summary of the five-mine data is given in
table 4.
TABLE 4. - Radon-daughter control costs for five large uranium mines (10)
Mine and year
Mine average
WL's
1
Ore output, 1
Total costs
103 tons
per ton2
132
$0.76
115
.86
79
.92
237
.57
278
.57
154
.71
119
.67
184
.87
104
.84
212
.55
276
.66
150
.88
84
.64
154
.51
78
.74
157
.62
201
.67
113
.81
Mine D:
1967
1968 3
Mine E:
1966
1967
1968 3
Mine F:
1966
1967
1968 3
Mine G:
1966
1967
1968 3
Mine H:
1966
1967
19683
Average: ^
1966
1967
19683
2.0
.8
.4
2.2
1.1
.5
1.6
1.4
.5
2.3
1.3
.7
1.5
1.1
.6
2.03
1.18
.55
Original WL data, given for each half of each year, were weighted by ore
output for each 6-month period to arrive at these yearly averages.
2Includes new capital costs at 10-yr writeoff.
3First half of 1968 only.
^Some values recalculated from published table (10, table 3).
The mathematical analysis, cost versus working level, of the three-mine
data yielded a linear equation, and that of the five-mine data an exponential
equation. Their calculations indicate that to keep the highest exposure under
0.3 WL, the mine average must be 0.15 WL. Extrapolating to this low level,
they estimated a cost of approximately $1.05 per ton. Thompkins (11) took
exception to this calculation and drew another curve through their data, indi-
cating that it would be impossible to achieve less than a 0.5-WL average,
regardless of how much money was spent on ventilation.
ADL Study
The study by Arthur D. Little, Inc. (ADL) for the Federal Radiation Coun-
cil CO is the most thorough evaluation of costs relative to radon-daughter
control that is available. ADL personnel selected a sample of 26 underground
uranium mines that would represent the underground uranium mining industry.
In addition, they covered the more important producing regions, including
large and small mines, old and new mines, and mines with high and low emana-
tion rates. For early 1970, at the time of radon-daughter sampling, the
26 mines represented 29 pet of the mines, 81 pet of the production, and 88 pet
of the underground employees in the United States.
The information supplied by each mine operator included working levels
and costs. Some operators furnished data on percentages of underground miners
receiving exposures in various working-level-month (WLM)1* ranges. They also
supplied detailed mine maps showing the location of ventilation holes, fans,
secondary air bags, measured working levels, and airflow at various points in
each mine. The measurements recorded were taken in March 1970. From all of
the working-level data, ADL personnel were able to calculate three figures to
characterize the situation at each mine:
1. Mine working-place average working level, which is the average of all
working level readings reported in working places and access ways on the mea-
surement day.
2. Maximum working level, which is the highest value reported in any
working place on the evaluation date.
3. The "last man" working-level-month, which is the highest 1969 expo-
sure recorded for an individual. The costs for ventilation and radiation con-
trol included fan power, maintenance, heating, and labor for ventilation and
sampling, as well as capital costs for ventilation holes and other ventilation
equipment.
After gathering the baseline information, ADL had a team of mining,
ventilation, and radiation control experts study each mine to establish the
changes that would be necessary to assure that a reading of 0.3 or 0.6 WL
would not be exceeded in any working or travel area. These would then equate
4 or 8 "last man" WLM exposures. A design was developed for each mine to
assure satisfying the 4 and 8 WLM per year standards. The incremental costs
were calculated using standard unit costs. New investments such as additional
drill holes, fans, bulkheads, and air heaters were included. The additional
operating costs for power, labor, fuel, and supplies were also considered.
Amortization for new capital items was done against 1 year's ore production
from the mine. This procedure does result in higher costs than would be
expected if the amortization was done more on a basis of the total ore
reserves, if these had been known. Data extracted from the ADL report are
given in table 5.
^Inhalation of air containing a radon-daughter concentration of 1 WL for
173 hr results in an exposure of 1 WLM.
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ANALYSIS
Since these studies spanned a 5-year period, the cost data should be put
on a common base before analysis. The Consumer Price Index (CPI), also known
as Cost of Living Index, was used to change all costs to 1967 dollars (1967$);
hence CPI = 100 in 1967.
The Federal Radiation Council data (6) first required a calculation of
the estimated tonnage for the mines over a 10-year period. In 1965, the
11 mines (table 1) produced over 20 pet of the total U.S. production,5 which,
at exactly 20 pet, amounts to 872,523 tons of ore. Therefore, the 10-year
production is over 8.73 million tons. Table 6 gives the ventilation control
costs converted to dollars per ton. The three small mines produced approxi-
mately 87,252 tons of uranium ore in 1965, or approximately 0.52 million tons
in the 6-year analysis period (table 6). The working level month figures and
1967 dollars per ton are plotted in figure 1.
TABLE 6. - Federal Radiation Council Report 8 (6) uranium mine ventilation
cost data converted to 1967 dollars per ton
Item
Total cost,
millions
Cost per ton
Mine index
or average WL
WLM
In 1965$
In 1967$
11-mine study (10-yr):
Minimum ventilation.
3-mine study (6-yr):
Minimum ventilation.
Control to 1.5 WL...
$4.8
11.8
19.3
.18
1.01
$0.55
1.35
2.21
.34
1.93
$0.58
1.43
2.34
.36
2.04
ho
2
1
^-20
31.5
120
24
12
2150
18
^-Estimate of average WL with normal metal mine ventilation practice.
2Midrange, 12.5 WL, used to calculate WLM.
3Average concentration.
It is assumed that the costs supplied to Spencer (10) by the mine owners
are CPI-corrected for each year during 1966-68. Table 7 summarizes the data
and the conversions to 1967 dollars (1967$). These data and the production-
weighted averages for all eight mines are also plotted in figure 1. As
expected, because of the much greater tonnage, the weighted average is very
close to the values for the five larger mines. Cross (5) pointed out that
Spencer ( 10) neglected the succeeding years' equipment amortization and return
on investment. This may have resulted in a cost understatement of 20 percent;
the corrected data are also plotted in figure 1.
5Total U.S. production in 1965 was 4,362,614 tons (3).
10
TABLE 7. - Uranium mine ventilation cost data from Spencer (10) ,
converted 1967 dollars per ton
Item
Cost per ton
Cost, 1967 dollars
per ton
Average
WL
WLM
Three smaller mines:
1966
$0.24
.52
1.26
.62
.67
.81
$0.25
.52
1.21
.64
.67
.78
1.66
1.50
.55
2.03
1.18
.55
20
1967
18
1968
6.6
Five larger mines:
1966
24
1967
14
6.6
10
9
8.
7.
6.
5. _
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1 1-mine study, FRC
—
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3-mine study, FRC
—
o
S larger mines, RMC
a
X
3 smaller mines, RMC
D
Weighted average of RMC data
:
A
a o
V
+
a
RMC weighted average
corrected for 20% cost error
by Cross (5)
Average cost and WLM data, ADL
B
A
X
o
A
Estimated weighted average of
ADL data
—
+ A
8
+
+
8
o
—
X
—
V
—
1 1
1 1 1 MM
X
1
1
1 1 1 1 III
I I I I I I II
10. I00.
AVERAGE ANNUAL EXPOSURE, WLM
1,000.
FIGURE 1. - Cost per ton for ventilating uranium mines.
11
The ADL study (1) had as its sole purpose to derive the total costs and
impacts of decreasing the allowed radon-daughter exposure. The data for all
26 mines are given in table 5. There is considerable scatter in the informa-
tion; therefore, care was taken to arrive at reasonable averages. The authors
of the ADL report provided production-weighted incremental costs to arrive at
8 and 4 WLM exposures (table 5), but two key items are missing from the ADL
survey — "present weighted average cost per ton" and "present average working
level." These are estimated in two ways, arithmetic averages and using the
observed differences in the average value and the ADL production-weighted
average costs. These are given in table 8, and plotted in figure 1.
TABLE 8. - Average ventilation costs and working place
radon-daughter concentrations
Cost per ton,
1970$
Cost per ton,
1967$
Average WL
Item
Using
table 5
averages
Using
table 5
weighted
averages
Using
table 5
averages
Using
table 5
weighted
averages
Average WLM
Present conditions
Last man = 8 WLM. .
Last man = 4 WLM. .
1.88
2.69
5.19
1.03
1.53
2.76
1.66
2.38
4.59
0.91
1.35
2.44
0.487
!.451
*.226
5.8
5.4
2.7
1Ratio calculated from table 5 averages used to calculate average WL,
The best values from the three studies are plotted together in figure 2,
and a least-squares line, calculated in logarithmic space, has been drawn
through the data. The equation for this line is
1967$/ton = 3.134 (WLM)"0- 3715,
(1)
with a correlation coefficient, R = -0.75.
The 95-percent confidence limit on the expected value of the mean is, in
1967$/ton, approximately $1.10±$0.07, and for a particular value of the mean
it is $1.10±$0.32. An equation was also calculated using the average val-
ues. This equation has a steeper slope and larger intercept:
and
1967$/ton = 4.616 (WLM)-0' **8 19,
R = -0.77.
(2)
In both cases, the fit is significant at the 0.01 level (99-percentile) , but
the first equation is used in the remainder of this paper since it includes
the corrections that are considered necessary. The exponential model
developed by Cross (5) from the individual mine data is given in cents per
pound U3O8 (1969 dollars) versus average annual exposure. By converting their
equation to dollars per ton (assuming 0.22 pet U3O3 ore grade) and 1967
dollars, it becomes
1967$/ton = 3.979 (12WL)-0-63.
(3)
12
r 4.
I
—
KEY
—
O 1 1-mine study, FRC
—
V 3-mine study. FRC
—
+ Weighted average of RMC
--■^^A
o
data corrected for 20% error
by Cross (5)
A ADL data with corrected cost
and WLM
A
V
o
/1967$/ton = 3.134 (WLM)"03715
+
/ R = -075
—
A
—
+
+
—
^""■"^■^o
V ^-x^^
—
1 1
Mill
II
1
1
I I 1 1 III I I
2 —
I. 10. I00.
AVERAGE ANNUAL EXPOSURE. WLM
FIGURE 2. - Costs for ventilating uranium mines versus average annual exposure with regression line.
This equation has a larger intercept and a much steeper slope than the
equation developed from weighted average costs and working levels. Higher
cost estimates for control to 1- to 2-WLM annual exposures results when this
equation is used.
APPLICATIONS
1,000.
Equation 1 can be used with some limitation to estimate the industry
average cost for ventilating uranium mines at any desired average working
level at any consumer price index and provide comparisons with other radiation
control costs.
13
The inflationary rise in the Consumer Price Index since 1965 is shown in
table 9. Since the data used in the analysis were converted to the 1967 base
CPI, it is a simple matter to multiply the calculated cost per ton by the new
CPI divided by 100, as follows:
$/ton = 3.134
CPI
100
(WLM)
-0.3715
= 0.03134 CPKWLM)-0'3715.
An example for CPI = 250 (1980$) is given in table 10 and figure 3.
TABLE 9. - Consumer Price Index (based on 1967 = 100)
1965....
94.5
1972
125.3
1979
217.6
1966....
97.2
1973
133.1
1980....
246.9
1967....
100.0
1974....
147.7
1981:
1968
104.2
1975
161.2
Jan. . .
260.7
1969....
109.8
1976
170.4
Feb...
263.5
1970
116.3
1977
181.5
Mar. . .
265.2
1971
121.3
1978
195.3
Apr . . .
266.8
TABLE 10. - Cost per ton at CPI = 250 (1980$)
for several average WLM exposures
Average WLM
Cost per ton
At CPI = 100
At CPI = 250
4
$1.87
$4.68
2
2.42
6.06
1
3.13
7.84
.7
3.58
8.95
(4)
14
30.
w"
i-
v>
o
o
■_l
o
IX
I-
z
o
o
:o.
^^^^ ^**s,n^ i
10.
^_ i
9.
^^ ^^j^H^
^ — J
8.
^^>^ ^ ""*
Sw i^^*^
7.
^H^^-^
6.
^^
^x\r*
^>«^
5.
4.
i
J"*"^
^^^
NS>^O^^P^^
3.
0.7
WLM " last man" t
r*"*"
^
1 WLM " last man
/ ***"•-
^^^o-^O^^T^-^
2.
2 WLM " last
man"-" T*""".*^^ ""^s>>Vn^ "^^^^ "^^^^ ^"""^^^
4 WLM * last man
1 .
.9
.8
.7
.6
.5
.4
.3
.2
.1
I I I I I I I
II 1
1 1 1 Ml 1 1 1 II
FIGURE 3.
I. 10.
AVERAGE ANNUAL EXPOSURE. WLM
Projected radiation control cost for different Consumer Price Indices and
average annual exposure.
100.
At this point, the "last man" exposure should be introduced. If an
average working level exposure of 4 WLM is maintained, some miners will be
overexposed. Therefore, we should make the projections based on limiting the
maximum exposure. Information in the ADL report (1_) indicated a factor of
1.478 between the average working-level-month exposure and the "last man"
exposure. After incorporating both "last man" exposure and consumer price
index, equation 1 becomes —
DPT = 0.03624 CPI (LME)-0'3715,
where DPT = dollars per ton corrected for CPI,
and LME = limiting miner exposure (the highest annual
exposure received by an underground employee)
(5)
15
Table 11 gives an example of several limiting exposures at a CPI of 250.
information, along with several other CPI's, is shown in figure 4.
This
TABLE 11. - Cost per ton at CPI = 250 for several
limiting miner exposures WLM
Limiting miner
expos
ure,
Average
WLM
Cost per ton
WLM
at CPI = 250
4
2.71
$5.41
2
1.35
7.00
1
.68
9.05
.7
.47
10.34
30.
20.
10.
9.
8.
c
o
7.
«■*
6.
<A
5.
co
H
4
»
o
o
3.
-1
o
a.
2
K
z
o
o
z
o
1
1-
.9
<
.8
o
.7
<
.6
cr
.5
.4
.3
.2
1. 10.
LIMITING MINER EXPOSURE, WLM
100.
FIGURE 4. - Project radon-daughter control costs versus limiting miner exposure WLM
for several Consumer Price Index values.
16
In looking at these projected costs for radiation control in uranium
mines, it is apparent that they are significant. The underground uranium ore
production in 1979 was approximately 6 million tons (8). Therefore, the esti-
mated present cost is over $32 million per year if the industry is truly main-
taining 4 WLM. If the limit is reduced to 2 WLM, the estimated total cost is
$42 million; for a 1-WLM limit, it is $54 million, and for a 0.7-WLM limit, it
is $62 million. Clearly, any change in permitted exposure levels can have a
serious economic impact on mining costs. Also, as mines become deeper and
larger than the mines in the 1965-70 base period, the total cost for ventila-
tion is going to increase significantly, unless other control measures, are
used to cut the ventilation requirements.
COST OF OTHER CONTROL MEASURES
Even with the present cost, we should be looking at all of the other
available control measures. In recent years there has been an attempt by the
Bureau of Mines and others to arrive at cost factors for other control tech-
niques. The U.S. Environmental Protection Agency (EPA) sponsored a 2-month
study that resulted in a report by Kown (9). This study considered the mine
as a whole and its total production of radon, 8.86 Ci/day. Some of the radon
reductions and costs given by Kown (9) are shown in table 12. Other control
measures such as mine pressurization, the use of highly reactive chemical
oxidants, and specialized mining techniques were discussed, but costs were
not calculated.
TABLE 12. - Costs for radon control from Kown (9)
Control measure
Radon reduction,
Ci/day
Cost per
ton
Activated charcoal
with bulkheading. . . .
1.01
2.95
3.01
$1.45
.34
4.32
Cost figures reported by the Bureau of Mines are usually for single
installations. For example, the materials cost of an 8- by 14-foot bulkhead
was $186 to $295 (]). Radon barrier sealant costs per square foot have been
$0.30 to $1.19 ($0.46 to $1.84 in 1980 dollars) (_4). The most expensive coat-
ing system was the least satisfactory material because it contained chopped
fiberglass. Field tests of sealants showed radon-stopping power of up to
75 percent; therefore, they can reduce the amount of ventilation needed to
control the radon-daughter concentrations to a given level.
Cost figures like these can be compared with the cost for ventilation
control. To accomplish this, the cost of a control measure must be expressed
in the same units as ventilation costs — dollars per ton — and the effect of the
new control measure must be defined. For example, cost per square foot is the
most convenient for sealant coatings, and this can be related to a cost per
ton by considering the surface area remaining in the excavation of typical
drifts. In a 6- by 7-foot opening, about 8.2 square feet of rock is exposed
around the periphery for each ton of rock removed; for a 12- by 14-foot
17
drift, about 4.1 square feet of surface is left per ton of rock removed.
Therefore, sealant coatings cost about $2 or $3 per ton (1980). This is con-
siderably less than the estimated $5.43 per ton for present radon-daughter
control.
CONCLUSIONS
The available radiation control cost information has been analyzed and
yielded the equation: Cost, 1967$/ton = 3.134 (WLM)-0*3715. Combining limit-
ing miner exposure, LME, and consumer price index, CPI, the dollars per ton
(DPT) can be estimated from DPT = 0.03624 CPI (LME)-0*3715. The 1967 cost per
ton for a number of average and limiting miner working-level-month exposures
has been calculated and converted to a 1980 CPI value. At a LME of 4 WLM, the
projected cost per ton for radiation control is $5.41. If the LME is reduced
to 0.7 WLM, the projected cost per ton is $10.34. These values are only
applicable to radiation control in U.S. sandstone-type mines. Considering
the projected costs per ton, any reasonable technology should be used in the
control of radon and radon-daughters.
18
REFERENCES
1. Arthur D. Little, Inc. An Assessment of the Ecomonic Effects of
Radiation Exposure Standards for Uranium Miners. Rept. to the Fed.
Radiation Council, November 1970, 2d ed. , 250 pp.
2. . Advanced Techniques for Radon Gas Removal. BuMines Open File
Rept. 60-75, May 1975, 209 pp.; available for reference at BuMines
facilities in Pittsburgh, Pa. , Denver, Colo. , Spokane, Wash. , and Twin
Cities, Minn.; at the National Library for Natural Resources,
U.S. Dept. of the Interior, Washington, D.C.; and at the Dept. of
Energy facility in Morgantown, W. Va. ; available from National Tech-
nical Information Service, Springfield, Va. , PB 243 898; BuMines
contract H0230022.
3. Baroch, C. T. Uranium. Ch. in BuMines Minerals Yearbook 1965. V. 1.
Metals and Minerals (Except Fuels), pp. 973-991.
4. Bates, R.C. , and J. C. Franklin. U.S. Bureau of Mines Radiation
Control Research. Proc. Conf. on Uranium Min. Technol. , Reno, Nev. ,
Apr. 25-29, 1977, 32 pp.
5. Cross, F. T. , C. H. Bloomster, P. L. Hendrickson, and I. C. Nelson.
Evaluation of Methods for Setting Occupational Health Standards for
Uranium Mines. Nat. Inst, for Occupational Safety and Health, NIOSH
Rept. 72-2, 1974, 237 pp.; available from Nat. Tech. Inf. Service,
Springfield, Va. , PB 237 744; NIOSH contract HSM-99-72-135,
Battelle-Pacif ic Northwest Laboratories.
6. Federal Radiation Council. Guidance for the Control of Radiation Hazards
in Uranium Mining. FRC Rept. 8, rev. September 1967, 60 pp.
7. Franklin, J. C, C. S. Musulin, and D. W. Thebeau. Research on Bulkheads
for Radon Control in Mines. Proc. Update on Uranium Min. Technol.,
Reno, Nev., Nov. 13-17, 1978, 11 pp.
8. Klemenic, J. Production Capability. Proc. Update on Uranium Min.
Technol., Reno, Nev., Nov. 13-17, 1978, 30 pp.
9. Kown, B. T. , V. C. Van der Mast, and K. L. Ludwig. Technical Assessment
of Radon 222, Control Technology for Underground Uranium Mines.
Bechtel National, Inc., San Francisco, Calif. Task 9, 1979, 61 pp.
10. Spencer, N. , L. Spittel, T. Towles, and G. Lady. Control of Radiation
Exposure in Uranium Mines: A Cost and Economic Analysis. Resource
Management Corp., Rept. UR-42, prepared for the Federal Radiation
Council, November 1968, 66 pp.
11. Thompkins, R. W. Radiation Control in North American Mines and Their
Effects on Mining Costs. Proc. 7th Internat. Min. Cong., Bucharest,
Romania, September 1972, pp. 1-11.
« U. S. GOVERNMENT PRINTING OFFICE : 1981 358-313/7175
3964
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